Boiler drop-plug



ORMICK AL BOILER DROP PLUG Maich 1933.

Filed Feb. 23, 1932 m'i'ek "/4 5. A

' INVENTOR ATTORNEY51 i BY 0 5 ww zzg A .J 2

Patented Mar. 7, 1933 UNITED STATES PATENT OFFICE GEORGE MCCORMICK, OF REDWOOD CITY, AND FRANK E. RUSSELL, OF ALAIEDA,

' CALIFORNIA 4 1301mm DROP-PLUG Application filed February 28, 193 2. Serial I 0. 594,568.

Our invention relates to that type of boiler-plugs which comprises essentially a dropplug member, releasable under predetermined temperature and pressure, inorder 5 to open direct communication between the steam space and the fire box, and thereby permit a jet of steam to pass into the fire box for a purpose and with an effect well known in the art. a

These boiler plugs, though applicable to various forms of boilers, are especially useful in locomotive boilers. They are located in the crown-sheet of the boiler and comprise an open ended body member fitted through said crown-sheet, a drop-plug member normally closing the upper end of the body member, and a cementing member uniting said body. and plug, and fusible under a given temperature or range thereof, to release said plug and allow 1t to drop through the body member and thereby open it to the passage of steam from the boiler into the fire box. The conditions under which the device thus functions, usually the unsafe lowering oh; the water level in the boiler, whereby the crown sheet is exposed to a dangerously high temperature; and the eflect of the steam 'et, either through audible warning, or in a ecting the fire, are well known and will require onl such reference to, them as will glve a ful understanding of the nature of our improve-.

ment as hereinafter set forth.

One object of our invention is to provide a boiler drop plug of the type mentioned, which is sim 1e and inexpensive in manufacture, capa 1e of ready application, and is sensitive, reliable and positive in operation.

Another object is, b the use of a plurality of such drop p ugs, to providefor steam jets in such number as will insure positive inhibitive effects as will be described.

To these ends, our invention consists in the novel construction, arrangement and combination. of the several members of the .device, and the application of said devices in plural numbers, aswill be hereinafter de-' scribed. I

In the accompanying drawing, we have ment of the crown sheet 0 upper end bein shown the device in its preferred form, it beingunderstood that changes may be made without departing from the spirit of the invention as defined by the claims hereunto ap ended.

n the drawing, Fig. 1 is a vertical central section of our boiler drop-plug showing it fitted in a plate which re resents a fraga boiler.

Fig. 2 is a top plan, and

Fig.3 is a bottom plan of the same.

Fig. 4.- is a fragmentary side elevation of v the upper portion of the body member.

Fig. 5 is a side view of the wrench for seating the body member in the crown :5 sheet. v

Fig. 6 is a vertical longitudinal section of a locomotive boiler showmg the application of a plurality of our drop-plug devices thereto. Fig. 7 is a cross section on the line 77 of Fig. 6. Fig. 8 is a diagrammatic plan of a crown-sheet showing a plurality L of our drop-plugs applied thereto.

Fig. 9 1s afragmentary vertical section showlng a modified form of plu 1 is a tubular, open-ended, body-member, made of metal, for example, bronze, or other suitable material. Its lower portion tapers upwardly and is externally threaded as shown at 2, said portion bein tapped through and ti htly seated in t e boiler crown-sheet 3. The up er portion 4 of the I body member rojects a we; thecrown-sh'eet and is prefera 1y uniformly. cylindrical, its

inwardl flanged at 5 to form the top orlfice .6 of t e body bore, and to form also the internal shoulder 7 at the base of said orifice. From this shoulder, which, as shown, is of greater diameter than the orifice 6, the hereof the bodymember no uniformly increases in diameter as shown at 8, towards its lower portion, which at 9 is angular in section to provide a Wrench 7 hold for the ap lication of a wrench to properly seat said ,member in the crown sheet. J

The bore of the body member thus comprises the top orifice 6 of, relativel small diameter and appreciable depth, the internal shoulder 7 of a greater diameter than the top orifice, the downwardly widening-middle portion 8, and the angular sectioned wrench-hold lower portion 9.

The releasable closure or drop-plug member is a metallic body characterized exte-' riorly by three portions, namely a sealing head-portion 10, a tongs-handling foot portion 11, and an intervening seal-protecting flange 12.

In the normal assemblage of parts, the closure or drop-plug member, handled by a pair of tonigsapplied to its foot portion 11,

ts its head portion 10 within the top orifice 6 of the'body member 1, said head portion having a diameter suficiently less than the diameter of said orifice to provide for the cementing member hereinafter mentioned, between their adj acent vertical surfaces, and having a depth equal to that of said orifice. The flange 12 of the drop-plug member lies directly under and against the internal shoulder 7 within the body bore at the base of the orifice 6, said flange having a diameter suficiently great to span said orifice with appreciable overla but free of the body bore side wall. "T e toot portion 11 of the closure member lies within the body bore with enough clearance to provide for the tongs by which the plug is set in place.

Between the adjacent vertical surfaces of the top orifice 6 of the body member 1 and the head portion 10 of the drop-plug member is theannular cementing member 13. This is composed of a suitable alloy, consisting of tin and lead or other composition adapted, under a predetermined temperature 'or range thereof to sufficiently soften or melt or fuse and thus weaken its adhesion, and permit the steam ressure in the boiler to force theplug mem er from its seat and .drop it into the fire box, thereby opening the body member to the passage of steam from the boiler into the fire box, after the manner and according to the purpose of boiler plugs of this type.

With the foregoing description in mind, certain features of novelty and improvement may now be referred to.

First, as to the cementing member 13 and its positional relation. As a vertically disposed annulus applied to relat1vel extensive surfaces, there is assurance 0 normal adherence, resulting in a dependable deference of loosening function, to await the predetermined temperature and pressure, rather than a premature release, such as is more apt to occur with a horizontally disposed cementing member.

Second, by exposing the upper end of the I vertically dlSPOSQd cementitious annulus 13 there is additional directly within the boiler,

vassurance of the proper and timely efi'ect upon said annulus as determined by the redetermined temperature, and this is in gontra'st with confining the cementing member wholly within the body member.-

Third, the width of the flange 12 of the drop-plug member hasan importance especially to be noted. By spanning the base of the .top orifice 6 of the body member and seating itself with appreciable contact overlap upon the internal shoulder 7 of said body member, though with good clearance from the side wall of the bore of said member, said flange completely covers the lower edge of the cementing member 13 and protects said member from the direct heat of the fire and the corrosive action of the products of combustion, thus leaving said member 13 to be afiected Wholly by the predetermined temperature and pressure within the boiler. The covering of the lower edge of the member 13 by the flange 12 is. thus in beneficial contrast with an assemblage of parts which may leave sai member 13 exposed in any part directly to the heat and gases of the firebox.

Fourth, the clearance of the drop-plug member with respect to the bore of the body member, and the downwardly increasing diameter of said bore are such that when the drop-plug member is released and forced from its seat, it will drop through the body member without the slightest liability of catching or obstruction. In order to further insure this result, all surfaces are made as smooth as possible. The necessity of precision in the functioning of boiler plugs of the type herein described, has resulted in bestowing upon their manufacture and testing, extreme care. In this connection attention is now directed to Fig. 4. Near the upper end of the body member 1, the exterior surface of said member is knurled or otherwise chased as shown at 1.4:- The purpose ot this is informative. llt the 'kniirllng or chasing 3 shows a marring such as might result from a blow, a tall or other accident, it is possible that the shock may have extended to and injured the cementing member 13. Therefore, opportunity is afi'orded, before placing the plug in use, to exercise such precaution as the circumstance may call for. Because the fitting of the body member .1 into the crown sheet is necessarily overhead work, the angular wrench hold 9 lies in the base of the bore of the body member, and a wrench is provided for rendering the screwing up of the body member in the crown sheet a matter of some convenience. This wrench is shown in Fig. 5 and is indicated as a whole by the numeral 15. It comprises an angular wrench portion 16, adaptedfor engagement with .the wrench hold 9 of the body member; an end projection 17, slightly smaller in I somewhat greater than 90 with relation to the center line of the wrench fit said handle havin a hand grip ,19 parallel with the wrenc fit, to prevent appl ing too much force when screwing the b0 y member into f and 23 the flues. 24 indicates the steamjets.

" It is to be noted by reference to Figs 6 and 8, the latter especially, that a plurality of the drop-plugs devices are fitted to the crown sheet 21, selectively distributed over the hottest portionthereof. The number of plugs will be in proportion to the gas area of the flues, or the horsepower of the boiler, in order to insure a sufficient volume of esca ing steam issuing from the plugs, to fill t e, flues and fire box, thereby smothering the fire and cooling the interior of the fire box, including the fire box sheets, to such an extent that the engineer and firemen are prevented from continuing operation of the boiler with resulting catastrophe, as has been the case on previous occasions when, though the releasable droplug has fallen,

the resulting sound has not een recognized, and operation continued until explosion resulted.

In the normal operation of a boiler, that is to say, when the water level therein is maintained at a proper height above the ,crown sheet, the cementing material or alloy securing the drop-plug member is protected by comparatively cool .water covering the crown s eet and surrounding the upper portion of the device which projects above said sheet, in which portion the drop-plug and cementing alloy are located, thereby preventing t em from becoming hot enough vto weaken the alloy and permit the pressure to force the drop-plug down. Moreover, the

space within the bore offthe body member below the drop-plug is practically a dead air space, and this, together with the covering effect of the flange 12 upon the lower edge of the alloy, furnishes additional protection against premature heating.

When the level of the water is permitted, by carelessness or by failure of boiler feed devices, to fall below the normal and safe height above the crown-sheet, and the ropplug devices are no longer protected by surrounding water, their heat will increase until the predetermined temperature is reached, whereupon the alloy will melt and the drop-plug member will be forced out from the body member and will fall into the fire box. The esca e of the steam as shown by the plurality 0 jets 24, will fill the flues 23 and the fire box 22 with steam in sufiithe case of oil-firedboilers, in which the combustion of the fuel frequently results in the deposition upon the 'walls of the firehave found it desirable to cover the lower endof the drop-plug member with a body of fusible material, as'illustrated in Fig. 9. This body of fusible material, indicated at 25, may be, and preferably is, the same alloy or metal that forms the cementing ring 13. It completely fills the space between the flan e 12 and gri plug an the walls of't e body, and its lowbox ofa layer of hard cohesive carbon, we

portion 11 of the 30 er exposed surface is preferably concave, as

shown.

The object of the plug covering body of fusible material 25 is to prevent the deposition of carbon upon the lower exposed portion of the drop-plug member and in the space between it and the walls of the body, experiment having indicatedthat the presence of such carbon afl'ects the reliability of release of the plug. Such carbon as may be deposited upon the exposed smooth surface of the fusible material 25, however, has no effect upon the release of the plug, because it is carried away by the initial melting of said material, which occurs slightly before the temperature of the cementing ring 13 reaches the melting point.

The fusible material 25 may be applied in any desired manner, preferably by dipping the preheated body, inverted, first into a bath of flux and then into the molten alloy up to the beginning of the threaded portion 2; and then dropping the plug member 10, also preheated and treated with flux, into the interior of said body while the latter is still partially immersed in the alloy. Upon lifting the body out of said alloy bath, the plug member descends to its final seat, with the cementing ring 13 held by capillary attraction between it and the body bore 6, and enough of the molten alloy is trapped above sald plug to cover its inner end as indicated "in Fig. 9, the concave surface of said covering body being formed by capillary action. Thus the entire assembly is accomplished in one simple operation.

We claim s 11 A boiler drop-plug comprising a bodymember having upon its exterior surface? near one end a relatively easily disfigurable chased section, said body member having also a through bore, which for a distance inwardly from the end within said chased Leeann? within the reduced end of the body-here and having also a llange of greater diameter than said reduced end, said flange being seated against the internal shoulder of the bore, with peripheral clearance from the side wall of said bore; and a cylindrical tusible cementing member between the opposing surfaces oi the reduced end of the bodybore and the portion of the drop-plug memm ber fitting therein.

2. A boiler drop-plug comprising a bodymember having a through bore, said here at one end, for a distance inwardly from said end, being of a diameter less than the 15 diameter of the remainder of the bore,' whereby an internal annular. shoulder is formed; a drop-plug member having at one end a portion adapted to hit within thereduced end of the body-bore and having also 5% a flange of greater diameterthan said reduced end, said flange being seated against the internalshoulder of the bore, with peripheral clearance from the side wall of said here; a fusible cementing member between the opposing surfaces of the reduced end of the body-bore and the portion of the drop-plug member fitting therein; and a body of fusible material filling the clearance space between said plug flange and the W body wall.

3. A boiler drop-plug comprising abodymember having a through bore, said bore having a smooth walled cylindrical portion of reduced diameter at its upper end and an 35 enlar ed portion at its lower end; an interior shoulder at the junction of said bore portions; a drop-plug, member having a flange and a smooth cylindrical portion thereabove, said flange being seated against d9 said shoulder and said cylmdrical portion fitting within the c lindrical portion of said bore; and a cylin er of fusible cementing -material filling the annular space between the smooth cylindrical surfaces of said bore 45 and said lug.

In testimony whereof we have signed our names to this specification; 0/

' GEQRGE MCCORMICK.

. FRANK E, RUSSELL.

Edd 

